Filters for removing contaminants in compressed gas and air in pneumatic systems are usually of a multi-layer construction. One such filter is a material containing a base of steel with a hot hardness of at least 600 on the Rockwell C scale and a carbon content of no more than 0.5 weight percent, an intermediate layer of a metal of the iron group, preferably nickel or cobalt, and a hard alloy working layer with a thickness of 0.2 to 1.0 mm. However, this material is not porous and cannot be used for separating aerosol moisture and oil from the air or gas flow.
Porous moisture separators made from ceramics or porous materials are widely known in technological filtering processes. One such porous permeable material is made of bronze and is obtained by sintering powder of particle sizes ranging from 0.05 to 1 mm. The permeability of a material of this type is below 70 percent. The pores of such a material consist of the openings between spheres of particles that are sintered together, and these pores quickly become clogged with dirt when contaminated compressed air is passed through them.
Another filter known in the art is made of a highly porous honeycomb material based on metals, or ceramics, and is obtained by modeling a porous structure-forming matrix. The three-dimensional structure of such a material represents a three-dimensional honeycomb mesh with honeycomb sizes ranging from 0.4 to 2 mm and open porosity ranging from 75 to 95 percent. However, these materials do a poor job of separating aerosol moisture from the fluid flow.
Another filter material is comprised of a stratal porous permeable material from the class of combined porous permeable materials (CPPM). A two-layer filter material is known in the art and is made of a filter base of nickel (serge screen 80/270), onto which a working layer of porous nickel carbonyl powder is formed. The filtering properties of such two-layer CPPMs allows a filtration fineness of 3 to 5 .mu.m. This degree of fineness is achieved due to design peculiarities of the two-layer material, obtained by spraying nickel carbonyl powder onto the nickel serge screen with subsequent sintering and cold rolling.
However, this stratal porous material does an inadequate job of separating small-size droplets of aerosol moisture from the compressed air or gas flow. This poor aerosol moisture filtering is due to a porosity of less than 70 percent, and moisture is held in the pores by adhesion forces and cannot be easily removed from the honeycomb structure of the porous material. The small contact zone of the capillary-porous powder layer prevents the fast removal of moisture from the fine porous layer, thereby sharply increasing the aerodynamic drag of the material.